Custom display sizes with Remote Desktop Connection

Microsoft’s Remote Desktop Connection is a nice piece of software. Wondering how to configure a desktop size so that it would fit perfectly into rotated monitor, I found the directions here to be very simple:

To set a custom display resolution in an .rdp file
Open the .rdp file in a text editor. Add or change the following settings:
desktopwidth:i:
desktopheight:i:
where is the resolution, such as 1680 or 1050.